Effect of Interparticle Field Enhancement in Self-Assembled Silver Aggregates on Surface-Enhanced Raman Scattering

The presence of so-called hot spots, regions with strongly enhanced electromagnetic field, is a critical property of a substrate enabling detection of surface-enhanced Raman scattering (SERS) signals at high enhancement levels. In this work, the effect of interparticle field enhancement on SERS signals was investigated comparing SERS spectra of ethylenediaminetetraacetic-disodium salt in the chemically produced colloids with isolated and aggregated silver nanoparticles using 473 and 532-nm wavelength excitation. The presence of aggregates in the colloidal solution resulted in SERS spectra that were insensitive to wavelength excitation and much richer in structural information and of higher resolution than the corresponding SERS spectra for the colloid with isolated nanoparticles. The experimental SERS spectra were found to be consistent with the finite-difference time-domain simulation results that explored the electromagnetic response of the isolated and aggregated nanoparticles. These results provide more evidence to suggest that the aggregate formation offers favorable electromagnetic properties increasing sensitivity of Raman spectroscopy.     

The theory and practice of constructing calibration curves in biodozimetry

The methodical peculiarities of experimental construction of regression "dose-effect" relationships used for the dose reconstruction are discussed. The method of computer simulations is applied to study the efficiency of different statistical procedures for plotting regression curves as well as the dependence of errors in dose prediction on the volume of examined material and on the choice of doses for a calibration curve. The causes of essential variability of calibrations obtained by different teams of researchers are discussed. A number of methodical recommendations is given for statistical processing of cytogenetic data. The procedure of constructing calibration dose dependence of the frequency of dicentrics on the basis experiments with in vitro gamma-irradiation of lymphocytes from blood samples of 5 donors is considered in detail. The expressions for statistical errors occurring in the dose reconstruction made on the base of the frequency of aberrations were derived and checked by the computer experiment.     

Labeling of aliphatic carboxylic acids using [11C]carbon monoxide

Here we present a protocol for labeling aliphatic carboxylic acids with the positron-emitting radionuclide 11C (t(1/2) = 20.4 min) at the carboxyl position using [11C]carbon monoxide via photoinitiated free radical-mediated carbonylation. A solution of an alkyl iodide in a homogenous binary organic solvent-water mixture is introduced into a high-pressure photochemical reactor containing [11C]carbon monoxide. Then the reactor contents are pressurized to 40 MPa and irradiated with ultraviolet light for 6 min. The labeled product is purified using HPLC. All manipulations with radioactivity including the labeling synthesis are carried out on an automated Synthia system. In a typical case, 3.19 GBq of purified [1-(11)C]1,10-decanedicarboxylic acid (with a specific radioactivity of 188 GBq/micromol) can be obtained within 35 min after the end of a 10-microAh bombardment. Compared to previous labeling methods, this protocol is compatible with a wider range of functional groups, utilizes less-sensitive precursors, and is less subject to isotopic dilution.     

Kinetics of semax penetration into the brain and blood of rats after its intranasal administration

The radioactive petide analogue Semax corresponding to the ACTH(4–10) sequence (Met-Glu-His-Phe-Pro-Gly-Pro) with a specific radioactivity of 56 Ci/mmol labeled with tritium at the C-terminal Pro was prepared. The labeled peptide was used for studying the kinetics of Semax penetration into rat brain and blood after its intranasal administration (50 μg/kg, 20 μl of solution) to nonbred white rats of body mass 200–250 g. It was demonstrated that 0.093% of the total introduced radioactivity per gram can be found in the rat brain 2 min after the administration, 80% of this radioactivity belonged to Semax, and the rest, to its metabolites. The peptide undergoes rapid enzymatic degradation, with the tripeptide Pro-Gly-Pro prevailing in biological samples relative to the total content of Semax and its metabolites.     

Comparative profiling identifies C13orf3 as a component of the Ska complex required for mammalian cell division

Proliferation of mammalian cells requires the coordinated function of many proteins to accurately divide a cell into two daughter cells. Several RNAi screens have identified previously uncharacterised genes that are implicated in mammalian cell division. The molecular function for these genes needs to be investigated to place them into pathways. Phenotypic profiling is a useful method to assign putative functions to uncharacterised genes. Here, we show that the analysis of protein localisation is useful to refine a phenotypic profile. We show the utility of this approach by defining a function of the previously uncharacterised gene C13orf3 during cell division. C13orf3 localises to centrosomes, the mitotic spindle, kinetochores, spindle midzone, and the cleavage furrow during cell division and is specifically phosphorylated during mitosis. Furthermore, C13orf3 is required for centrosome integrity and anaphase onset. Depletion by RNAi leads to mitotic arrest in metaphase with an activation of the spindle assembly checkpoint and loss of sister chromatid cohesion. Proteomic analyses identify C13orf3 (Ska3) as a new component of the Ska complex and show a direct interaction with a regulatory subunit of the protein phosphatase PP2A. All together, these data identify C13orf3 as an important factor for metaphase to anaphase progression and highlight the potential of combined RNAi screening and protein localisation analyses.     

Chromatin Central: towards the comparative proteome by accurate mapping of the yeast proteomic environment

Background  

Understanding the design logic of living systems requires the understanding and comparison of proteomes. Proteomes define the commonalities between organisms more precisely than genomic sequences. Because uncertainties remain regarding the accuracy of proteomic data, several issues need to be resolved before comparative proteomics can be fruitful.     

Results of the cytogenetic examination of the people taking part in the clean-up of the accident at the Chernobyl AES]

Chromosome preparations from peripheral blood cells of 117 subjects who took part in liquidation of Chernobyl NPP accident consequences in 1986 have been investigated. The number of chromosome aberrations has been shown to increase considerably. A short-term exposure has been found to be 5-7 times more effective than long-term one.